Design a Class Garden Bed

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1 Getting Started
2 Watch and Notice
3 Try It Together
4 Sketch Your Bed in Your Copy
5 Class Challenge
Pupil practice

1 - Getting Started ~4 mins

Illustration for Getting Started Here is the corner of the school grounds where we could build a class garden bed.

If we wanted to build a bed 2 metres long and 3 metres wide, what three different things would we need to measure or work out before we could actually build it and fill it with soil?

Teacher Notes

Take three or four hands-up ideas, not open call-outs. You are fishing for the three measures the module has covered: the length of edging round the outside (perimeter), the growing space inside (area), and the soil needed to fill it (volume). Don't name them yet — let the class surface them in their own words and hold the vocabulary for Watch and Notice.

👇 Mark your steps as done as you complete them.

+5 XP

2 - Watch and Notice ~8 mins

Watch two garden beds on the board. The first is a plain 2 m by 3 m rectangle. To find the edging, add the four sides: 2 + 3 + 2 + 3 = 10 m. To find the growing space inside, multiply length × width: 2 × 3 = 6 m².

Now watch the same bed shown as a solid, filled to a depth of 0.3 m. The soil is the growing space × the depth: 6 × 0.3 = 1.8 m³.

Some beds are not simple rectangles. Here is an L-shaped bed. We can draw one straight line to split it into two rectangles you already know how to measure, and the two areas add together to give the whole.

Teacher Notes

Three demonstrations, worked live on the board — don't read a paragraph over each.

2 m × 3 m rectangle: point to the edge and add the four sides aloud (2 + 3 + 2 + 3 = 10 m of edging), then the inside (2 × 3 = 6 m²). Hold out for the units — metres for the edge, square metres for the space.
Same bed as a solid, 0.3 m deep: the depth is the new wrinkle. Ask what changes now that it is a box, not a flat shape (6 m² of floor × 0.3 m deep = 1.8 m³).
L-shape: the interactive shows the L as a static picture. Draw the split line yourself on the IWB, straight down over the display, to cut it into two rectangles — the interactive does not do this for you. Then let the class read each rectangle and add the two areas to get the whole.

Keep the L light: it is not a fourth new idea, just the same length × width used twice and added. The point to draw out, not announce: the same bed can be measured three ways, and each answer needs its own kind of unit.

👇 Mark your steps as done as you complete them.

+10 XP

3 - Try It Together ~11 mins

Today we design one garden bed together and measure it three ways. We'll work through these on the board:

Drag the corners to make the bed 4 m long and 2 m wide.
Read the edging round the outside and the growing space inside.
Switch to the solid view and fill it to a depth of 0.3 m to find the soil.
Stretch the bed to 5 m by 2 m and watch every number change.

Shape Measurer

Teacher Notes

Talk this one through together — pupils take turns at the board and the class agrees or corrects out loud.

Work the numbered steps in order so each one adds something. 4 m × 2 m: edging 12 m, growing space 8 m². Switch to the 3D view and set the depth to 0.3 m — soil is 8 × 0.3 = 2.4 m³. Ask the class to predict what happens to each number before you stretch it to 5 m × 2 m. Watch for pupils reading the area figure but forgetting the m² unit — that is the slip to catch.

+15 XP

4 - Sketch Your Bed in Your Copy ~3 mins

COPYBOOK MOMENT

Illustration for Sketch Your Bed in Your Copy In your maths copy, sketch your own garden-bed design and label the length of every side along its edge.

Underneath the sketch, work out the three measures on separate lines and underline each answer:

Perimeter (add all the sides) = ? m
Area (length × width) = ? m²
Soil volume (area × depth of 0.3 m) = ? m³

Teacher Notes

Walk the row glancing at whether every side is labelled and whether the units (m, m², m³) are written on each answer line — this is whole-class copybook practice, not marking. The most common slip is a missing or wrong unit rather than wrong arithmetic.

+10 XP

5 - Class Challenge ~8 mins

Now design your own garden bed and prove it works, one design at a time. We'll work these together on the board.

Key point

First, a straight 3 m by 2 m bed. Then a 4 m by 3 m bed. Then we learn the L-shape edging move with one worked example on the board: an L made from a 3 m by 2 m rectangle joined to a 2 m by 2 m rectangle. Label every outer side, walk right round the outside only (the join inside gets no edging), and add those lengths for the perimeter. Add the two areas for the growing space, then multiply by a depth of 0.3 m for the soil. For the stretch, design an L-shaped bed with exactly 12 m² of growing area made from two rectangles that add together. For each one we find the edging, the growing space, and the soil at 0.3 m deep.

Shape Measurer

Teacher Notes

Practice round: pupils take turns at the board, class confirms, keep it brisk.

Rectangles first (use the interactive): 3 m × 2 m → edging 10 m, area 6 m², soil 6 × 0.3 = 1.8 m³. Then 4 m × 3 m → edging 14 m, area 12 m², soil 3.6 m³.

L-edging worked example (board only, interactive cannot build an L): draw the L from a 3 m × 2 m and a 2 m × 2 m, flush at one end. Draw the split line. Outer sides walking round: 3 + 2 + 1 + 2 + 2 + 4 = 14 m edging. Area: 3 × 2 + 2 × 2 = 6 + 4 = 10 m². Soil: 10 × 0.3 = 3 m³. Point to stress: the shared join is inside, so it is not counted in the edging.

Stretch: L with exactly 12 m² (e.g. 3 × 2 + 3 × 2, or 4 × 2 + 2 × 2). Same three measures each time.

Slip to catch: counting the inner join in the perimeter, or dropping the unit (m, m², m³) on any answer.

+15 XP

Pupil practice

Module 4 · Measures: Length, Mass, Capacity, Area, Volume Measures

Lesson 58 · Design a Class Garden Bed

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This lesson is copyright of Coding Ireland 2017 - 2025. Unauthorised use, copying or distribution is not allowed.

Teacher Class Feed

1 - Getting Started ~4 mins

2 - Watch and Notice ~8 mins

3 - Try It Together ~11 mins

Shape Measurer

4 - Sketch Your Bed in Your Copy ~3 mins

5 - Class Challenge ~8 mins

Shape Measurer

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